The proposed project is to study the biochemical role of dna gene products of B. subtilis phage SPPl, which uses the host DNA polymerase III for its DNA replication after modifying the enzyme complex. Restriction endonuclease EcoRI cleaves the genome into 15 fragment, of which two fragments contain all the dna genes and the origin of DNA replication. The genes are to be amplified using B. subtilis plasmid vectors and the gene products will be identified using mini-cell system. The identified products will be used to reconstruct the holoenzyme of polymerase III in an in vitro system. The recently discovered restriction-modification enzymes in competent cells are to be purified and their role in recombination will be studied by a proposed new in vitro system.